The invention relates to vehicle having a pinion starter for an internal-combustion engine, which includes a low-voltage onboard power supply system and a high-voltage onboard power supply system, and wherein the pinion starter has an electric motor and a solenoid switch.
In the case of vehicles having an automatic motor start/stop function in comparison to a conventional motor vehicle where only cold starts are carried out at the start of a drive, the number of starting operations of the internal-combustion engine has clearly increased. This applies particularly to hybrid vehicles, where, after an automatic stop of the internal-combustion engine and during an electric drive, the internal-combustion engine is additionally started.
According to the state of the art, starting systems for internal-combustion engines of hybrid vehicles are known which include a high-voltage starter; see, for example, German Patent document DE 10 2009 057 263 A1.
It is an object of the invention to provide an improved vehicle having a pinion starter for an internal-combustion engine, which includes a low-voltage onboard power supply system and a high-voltage onboard power supply system, and wherein the pinion starter has an electric motor and a solenoid switch.
This and other objects are achieved according to the invention by a vehicle having a pinion starter for an internal-combustion engine which includes a low-voltage onboard power supply system and a high-voltage onboard power supply system and wherein the pinion starter has an electric motor and a solenoid switch. The electric motor is constructed as a polyphase machine, which can be supplied with electric power from the high-voltage onboard power supply system, and the solenoid switch can be electrically powered by the low-voltage onboard power supply system.
This means that the pinion starter can be integrated in a vehicle having a low-voltage onboard power supply system and a high-voltage onboard power supply system such that the electric motor is designed to be high-voltage-compatible and is supplied with electric power from the high-voltage onboard power supply system, and the solenoid switch is electrically powered by the low-voltage onboard power supply system.
According to a further embodiment of the invention, the pinion starter includes a power electronics unit which controls the polyphase machine and the solenoid switch, and which can be electrically supplied by the high-voltage onboard power supply system and inverts electric power from the high-voltage onboard power supply system.
This means that the pinion starter has a power electronics unit which bidirectionally exchanges automatic control and control signals with the polyphase machine. The power electronics system automatically controls the polyphase machine and supplies the polyphase machine with inverted electric power from the high-voltage onboard power supply system.
In addition, it is advantageous for the motor vehicle to have a control device, and for the control device to bidirectionally communicate with the power electronics unit. The power electronics unit or the control device unidirectionally exchanges control signals with the solenoid switch and controls the solenoid switch. Accordingly, the control device can transmit control parameters and automatic control parameters for the control of the polyphase machine to the power electronics unit, and can transmit control parameters for the solenoid switch to the solenoid switch or the power electronics unit.
According to another embodiment of the invention, the vehicle is constructed as a hybrid vehicle, and the pinion starter can carry out cold starts, warm starts and reflex starts. A cold start is a start at the beginning of a drive. A warm start is an additional start of the internal-combustion engine during the actual drive, for example, after an automatic motor stop at a red traffic light or an additional start of the internal-combustion engine during a purely electrical acceleration. A reflex start is a start of the internal-combustion engine when the internal-combustion engine is coming to a stop, i.e. is still rotating.
Furthermore, it is advantageous for the control device to perform an automatic rotational speed detection of the internal-combustion engine and an automatic rotational speed detection of the polyphase machine, and for the power electronics unit to engage the pinion in a motor gear ring when the rotational speed of the polyphase machine is synchronized with the rotational speed of the internal-combustion engine.
In the case of a reflex start, it is also contemplated for the rotational speed of the motor that is coming to a stop and therefore the rotational speed of the polyphase machine and thus of the starter pinion to be monitored, and, at a rotational speed synchronous with the rotational speed of the motor ring gear, for the pinion to engage in the motor ring gear.
In addition, the power electronics unit is constructed with a galvanic isolation. This is particularly advantageous because the power electronics unit is electrically connected with the high-voltage onboard power supply system as well as with the low-voltage onboard power supply system. The galvanic isolation has the result that low-voltage onboard power supply system will be free of potentials from the high-voltage onboard power supply system.
According to a particularly preferred embodiment of the invention, the power electronics unit and the polyphase machine are constructed to be air-cooled.
The polyphase machine is preferably constructed as an asynchronous machine. The power electronics unit and the polyphase machine can then be further developed in a particularly cost-effective and robust manner.
The invention is based on the following considerations. In the case of hybrid vehicles (plug-in hybrid vehicles or vehicles having a motor stop/start function), a starting of the switched-off internal-combustion engine can be carried out during a driving operation of the vehicle. Such a start is called an additional start and is carried out by way of a high-voltage driving machine or a pinion starter from a separate 12-volt additional-start onboard power supply system. It is disadvantageous that a separate 12-V additional-start onboard power supply system, in addition to a 12-V basic onboard power supply system, as a rule, requires a separate additional-start accumulator and a coupling element between the 12-V basic onboard power supply system and the 12-V additional-start power supply system for recharging the additional-start accumulator.
Depending on the machine concept of the driving machine, an additional start by way of a high-voltage driving machine requires a high torque margin in the driving machine for starting power to be applied parallel to the electric driving. This torque to be used as the margin is not available for electric driving.
Therefore, according to the invention, a high-voltage pinion starter is integrated as a starting system for cold, warm and reflex starting operations in the case of hybrid vehicles. The advantage of a high-voltage pinion starter consists of the geometric and electric similarity to a conventional pinion starter. This concerns the geometric design and the interfaces of a high-voltage pinion starter. A high-voltage pinion starter with a high-voltage-compatible driving unit has a starter pinion behavior with a 12-V solenoid switch and an overrunning clutch construction similar to a conventional pinion starter. In addition, the high-voltage pinion starter can be integrated in a space that is comparable to that of a conventional pinion starter. The motor core with the primary winding and the secondary winding has a high-voltage compatible construction while taking into account touch voltage defaults for high-voltage systems.
A high-voltage pinion starter offers several advantages: while utilizing spaces known for conventional internal-combustion engine vehicles, in the case of hybrid vehicles, additional-start demands can be converted without enabling a high-voltage driving machine for additional starts and without integrating an additional onboard power supply system with a booster accumulator and a DC converter in the vehicle.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawing.